Site marker visible under multiple modalities

ABSTRACT

A site marker is provided that includes a generally hollow body defining a cavity. A deployment line within the site marker positions at least one marker element within the body portion. The deployment line has a first end that is fixedly secured to a first end of the body portion and a second end that is secured to a second end of the body portion. The deployment line is pre-biased so as to pull the first end of the body portion towards the second end of the body portion, and thereby expand the body portion.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.11/561,919, filed Nov. 21, 2006, which is a continuation-in-part of U.S.application Ser. No. 11/242,334, filed Oct. 3, 2005, which is acontinuation-in-part of U.S. application Ser. No. 10/964,087, filed Oct.13, 2004, the priorities of which are claimed under 35 U.S.C. §120, andthe contents of which are incorporated herein by reference in theirentirety, as though set forth in full.

FIELD OF THE INVENTION

The present invention relates generally to site markers for breastbiopsy procedures. More specifically, the present invention relates tosite markers that are visible under multiple modalities.

BACKGROUND OF THE INVENTION

In the diagnosis and treatment of breast cancer, it is often necessaryto perform a biopsy to remove tissue samples from a suspicious mass. Thesuspicious mass is typically discovered during a preliminary examinationinvolving visual examination, palpation, X-ray, magnetic resonanceimaging (MRI), ultrasound imaging or other detection means.

When a suspicious mass is detected, a sample is taken by biopsy, andthen tested to determine whether the mass is malignant or benign. Thisbiopsy procedure can be performed by an open surgical technique, orthrough the use of a specialized biopsy instrument. To minimize surgicalintrusion, a small specialized instrument such as a biopsy needle isinserted in the breast while the position of the needle is monitoredusing fluoroscopy, ultrasonic imaging, X-rays, MRI or other suitableimaging techniques.

In a relatively new procedure, referred to as stereotactic needlebiopsy, the patient lies on a special biopsy table with her breastcompressed between the plates of a mammography apparatus and twoseparate X-rays are taken from two different points of reference. Acomputer then calculates the exact position of the mass or lesion withinthe breast. The coordinates of the lesion are then programmed into amechanical stereotactic apparatus which advances the biopsy needle intothe lesion with precision. At least five biopsy samples are usuallytaken from locations around the lesion and one from the center of thelesion.

Regardless of the method or instrument used to perform the biopsy,subsequent examination of the surgical site may be necessary, either ina follow up examination or for treatment of a cancerous lesion.Treatment often includes a mastectomy, lumpectomy, radiation therapy, orchemotherapy procedure that requires the surgeon or radiologist todirect surgical or radiation treatment to the precise location of thelesion. Because this treatment might extend over days or weeks after thebiopsy procedure, and the original features of the tissue may have beenremoved or altered by the biopsy, it is desirable to insert a sitemarker into the surgical cavity to serve as a landmark for futureidentification of the location of the lesion.

Known biopsy site markers have been found to have disadvantages in thatthe site markers are not visible under all available modalities.Moreover, because of this problem, when cancer is found at a biopsy sitethat has been previously marked with a site marker, due to the poorvisibility of the biopsy site marker under ultrasound or othervisualization modalities, the patient must undergo an additionalprocedure that places an additional device the biopsy site to enable thesurgeon to find the biopsy site in subsequent procedures. One knowntechnique has been to place a breast lesion localization wire at thebiopsy site. The localization wire is typically placed at the biopsysite via mammography and/or ultrasound.

Accordingly, there is a need for site markers made from biocompatiblematerials that are visible under various modes of imaging to reduce thenumber of procedures that patients must undergo in detection andtreatment of cancer.

SUMMARY OF THE INVENTION

A site marker is provided that includes a generally hollow body defininga cavity. The site marker is formed into a predeployment configurationwhereby the site marker is compressed into a predetermined size andshape to as to be readily positionable within a deployment device. Thesite marker expands from the first predeployment position to a secondpost deployment configuration upon insertion into the body. A thread ordeployment line (e.g., thread, filament, wire) is attached to andextends between a forward end and a rearward end of the body portion. Atleast one marker element with a through opening (e.g., ring, tube,helical shape) is included. Accordingly, the deployment line is receivedin the through opening such that the marker element may selectivelyslide along the deployment line. This limits migration of the markerelement within a body. In another embodiment, a site marker is providedwith a filament that may be used either alone or in addition to adeployment line to further hold the marker element in place at an end ofthe site marker. In yet another embodiment, a deployment line is ahollow tube, and a marker element is able to fit inside of the hollowdeployment line.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the invention will beapparent from the following detailed description and the appendedclaims, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of a biopsy site in a human breast showingthe breast in section and one or more site markers being implanted inthe biopsy cavity using a site marker delivery system;

FIG. 2A is a side elevational view of a site marker according to a firstembodiment of the present invention;

FIG. 2B is an end elevational view of the site marker of FIG. 2A;

FIG. 3A is a side elevational view of a site marker according to asecond embodiment of the present invention;

FIG. 3B is an end elevational view of the site marker of FIG. 3A;

FIG. 4A is a side elevational view of a site marker according to a thirdembodiment of the present invention;

FIG. 4B is an end elevational view of the site marker of FIG. 4A;

FIG. 5 is a front elevational view of a site marker according to afourth embodiment of the present invention;

FIG. 6 is a side elevational view of a site marker according to a fifthembodiment of the present invention;

FIG. 6A is a side elevational view of a site marker according to a sixthembodiment of the present invention;

FIG. 7 is a perspective view of a site marker according to a seventhembodiment of the present invention;

FIG. 7A is a perspective view of a site marker according to an eighthembodiment of the present invention;

FIG. 8A is a side elevational view of a site marker according to a ninthembodiment of the present invention;

FIG. 8B is an end elevational view of the site marker of FIG. 8A;

FIG. 9 is a side elevational view of a site marker in accordance with atenth embodiment of the present invention;

FIG. 10A is a side elevational view of a site marker in accordance withan eleventh embodiment of the present invention;

FIG. 10B is a side elevational view of the site marker of FIG. 10A in apre-deployment configuration;

FIG. 10C is a side elevational view of a site marker in accordance witha twelfth embodiment of the present invention;

FIG. 10D is a side elevational view of a site marker in a pre-deploymentposition in accordance with a thirteenth embodiment of the presentinvention;

FIG. 10E is a side elevational view of the site marker of FIG. 10D in apost-deployment position;

FIG. 11A is a side elevational view of a site marker in accordance witha fourteenth embodiment of the present invention;

FIG. 11B is a side elevational view of a site marker in accordance witha fifteenth embodiment of the present invention;

FIG. 12A is a side elevational view of a site marker in accordance witha sixteenth embodiment of the present invention;

FIG. 12B is an end view of the site marker of FIG. 12A in apre-deployment position;

FIG. 12C is a side elevational view of the site marker of FIG. 12A in apost-deployment position;

FIGS. 13A-13B are side views of a site marker in accordance with aseventeenth embodiment of the present invention;

FIG. 13C is a side view of a site marker in accordance with a eighteenthembodiment of the present invention;

FIGS. 13D-13E are side views of a site marker in accordance with annineteenth embodiment of the present invention;

FIG. 14A is a front view of a site marker in accordance with a twentiethembodiment of the present invention;

FIG. 14B is a side view of the site marker of FIG. 14A;

FIG. 14C is a side elevational view of the site marker of FIG. 14A;

FIG. 15A is a side elevational view of a site marker in accordance witha twenty first embodiment of the present invention;

FIG. 15B is a side elevational view of a site marker in accordance witha twenty second embodiment of the present invention;

FIG. 15C is a side view of the site markers of FIGS. 15A and 15B in apre-deployment position;

FIG. 15D is a side elevational view of a site marker in accordance witha twenty third embodiment of the present invention;

FIG. 16A is a partial cross section of if the site marker of FIG. 10E ina post-deployment position;

FIG. 16B is a partial cross sectional view of a site marker in apost-deployment position, with the permanent marker shown in perspectiveview, in accordance with a twenty fourth embodiment of the presentinvention;

FIG. 16C is a partial cross sectional view of a site marker in apost-deployment position in accordance with a twenty fifth embodiment ofthe present invention;

FIG. 16D is a partial cross sectional view of a site marker in apost-deployment position in accordance with a twenty sixth embodiment ofthe present invention; and

FIG. 16E is a partial cross sectional view of a site marker in a postdeployment position, with a partial cross sectional view of thedeployment line in accordance with a twenty seventh embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a perspective view of a human breast 10 beingimplanted with a site marker 12 according to an embodiment of thepresent invention. At a biopsy site 14 is a lesion 16 from which atissue sample has been removed, resulting in a biopsy cavity 18. One ormore site markers 12 are implanted in the biopsy cavity 18 using amarker delivery system 20, as shown in FIG. 1. In one embodiment, themarker delivery system 20 is slidably advanced through an inner lumen 22of a biopsy device (not shown), which avoids the need to withdraw thebiopsy device and thereafter insert the marker delivery system 20.Delivering the site marker 12 in the biopsy cavity 18 withoutwithdrawing the biopsy device reduces the amount of tissue damage andenables more accurate placement of the site marker 12. The markerdelivery system 20 illustrated in FIG. 1 is exemplary only and it isunderstood that the site marker embodiments disclosed herein aresuitable for use with other marker delivery systems.

FIGS. 2A-8B illustrate suitable exemplary site marker embodimentsaccording to the present invention. In general, the site markersdescribed herein are made from biocompatible materials such as, but notlimited to, titanium, stainless steel, and platinum. These materialshave appropriate densities for radiographic imaging, appropriate surfacecharacteristics for ultrasonic imaging, and appropriate magneticcharacteristics for magnetic resonance imaging. The site markers thatwill be described below are preferably made from titanium; however, itis understood that any suitable biocompatible material may be used.

Referring initially to FIGS. 2A and 2B, a site marker 24 includes aplurality of balls 26 sintered together to form a unitary body. Theballs 26, as shown, vary in size and are sintered together randomly suchthat there is no structured or predetermined equidistance between thecenters of the balls 26. In other embodiments, the size of the balls 26may be generally uniform, or the balls 26 may be sintered together suchthat the centers of the balls 26 are aligned in a predetermined manner.As illustrated in FIGS. 2A and 2B, one embodiment of site marker 24measures approximately 1.5 mm in diameter (FIG. 2B) and 3 mm in length(FIG. 2A). As those skilled in the art will appreciate, when the sizeand sintering pattern of the balls 26 are modified, the size, shape anddimensions of the site marker will also vary. The balls 26 may beconstructed from any biocompatible material with suitable echogenicproperties such as, but not limited to, titanium, stainless steel, orplatinum.

FIGS. 3A and 3B illustrate another embodiment of the invention havingirregularly shaped particles or bits 28 that are sintered together toform site marker 30. The particles, as shown in FIGS. 3A and 3B, areexaggerated to illustrate the random shapes of the particles 28. Inapplication, however, the edges of the particles are sufficiently smoothso as to not damage any tissue. The particles can be substantiallysimilar in size and shape, or they may vary as shown in FIGS. 3A and 3B.The particles 28 may be constructed from any biocompatible material withsuitable echogenic properties such as, but not limited to, titanium,stainless steel, or platinum.

In another aspect of the invention, the particles 28 may be sufficientlysmall such that, when sintered together, the resultant site marker 32appears to form a porous metal, as shown in FIGS. 4A and 4B.

FIG. 5 shows another embodiment of a biopsy site marker 34 made from acontinuous strand of wire 36. To form the biopsy site marker 34, thewire 36 is fed into a molding cavity (not shown). When the wire 36reaches the back wall of the cavity, it folds over onto itselfconforming to the shape of the molding cavity. The wire 36 is compressedinto a mass that resembles a ball of yarn. Inherently, the size andshape of the site marker 34 is dependent upon the size and shape of themolding cavity. The wire 36 may be constructed from any biocompatiblematerial with suitable echogenic properties such as, but not limited to,titanium, stainless steel, or platinum.

FIG. 6 shows a thin-walled hollow site marker in the form of a capsule38 having an open end 40. A cap 42 is attached to the open end 40 by aweld 44. The capsule 38 is designed to resonate at a predeterminedultrasound frequency. In the event that the capsule 38 needs to resonateat more than one frequency, a resonant beam 46, as shown in FIG. 6A, canbe attached to the inner surface wall of the cap 42 so that the beamresonance is transmitted through the wall of the capsule. The capsule 38may be constructed from any biocompatible material with suitableechogenic properties such as, but not limited to, titanium, stainlesssteel, or platinum.

FIGS. 7 and 7A show site marker 48, 50 in the form of a rod 56, 58having drilled holes 52, 54 throughout the body of the rod. Site marker48 of FIG. 7A is a solid rod, whereas site marker 50 of FIG. 7 is ahollow rod or tube. The holes in both rods 48, 50 may be drilled in arandom or in a predetermined pattern. The rod 56, 58 may be constructedfrom any biocompatible material with suitable echogenic properties suchas, but not limited to, titanium, stainless steel, or platinum.

FIGS. 8A and 8B illustrate another embodiment of a site marker 60 thatincludes ball or bits 62 of material that are visible under one or moreimaging modalities, and dispersed in a block of material 64 that isdifferent than the balls or bits 62. The balls or bits 62 may beconstructed of titanium, stainless steel or other suitable material thatare visible under more than one imaging modalities. In addition, theballs or bits 62 of material may be contacting each other within theblock 64 and may vary in size and shape. In one embodiment, the block ofmaterial 64 is a biocompatible material such as epoxy. In anotherembodiment, the block of material is constructed of a bioabsorbablematerial that is absorbed by the patient's body such that only the balls62 remain at the biopsy site.

FIG. 9 illustrates another embodiment of a site marker 70 that is madein accordance with the present invention. Site marker 70 is a unitarybody made of biocompatible material or a combination of biocompatiblematerials that are visible under one or more imaging modalities. Marker70 may be hollow or solid. According to one aspect of the invention,marker 70 further includes a plurality of depressions 72 formed on anouter surface 74 of marker 70. Depressions 72 may be formed on surface74 so as to be set a predetermined distances apart from one another ormay be randomly formed on outer surface 74. Depressions 72 may also beformed so as to have a variety of shapes. In one embodiment, depressions72 have a parabola shape, with a length of at least about 0.25 mm.

In another embodiment, FIG. 10A discloses yet another alternativeembodiment of a site marker 80. Site marker 80 includes a generallyhollow body portion 82 that is flanked by closed ends 84, 86. Positionedwithin body portion 82 is a smaller permanent marker 88 that is capturedtherein. However, permanent marker 88 need not be attached to bodyportion 82 in any way. Permanent marker is preferably constructed of asuitable material that will not biodegrade within the body and which maybe viewed under multiple imaging modalities, such as Magnetic ResonanceImaging (MRI). Examples of suitable materials for permanent marker 88include, but are not limited to, titanium, stainless steel, ceramic,carbon, nickel titanium, and glass.

In one embodiment, body portion 82 is constructed of a bioabsorbablematerial such as polyglycolic acid (PGA), polylactic acid (PLA),hydrogel, collegen-based material or any other suitable material. Thebioabsorbable material may be woven into a flexible mesh that hasopenings formed therein that are sized so as to be smaller thanpermanent marker 88 such that permanent marker 88 cannot escape bodyportion 82. After installation in a biopsy cavity, over a predeterminedtime period such as three weeks to six months, body portion 82 isabsorbed by the body, such that only permanent marker 88 remains withinthe body at the biopsy cavity. Because permanent marker 88 is capturedwithin body portion 82 prior to absorption thereof by the body,permanent marker 88 is restricted from migrating from within the biopsycavity. Indeed, movement of permanent marker 88 is limited to theinternal cavity defined by body portion 82. This insures that permanentmarker 88 remains within the biopsy cavity to permit follow-up imagingof the biopsy site.

In one embodiment, prior to deployment into the biopsy site by asuitable deployment mechanism, site marker 80, and more specifically,body portion 82 is formed in a first pre-deployment configuration (asshown in FIG. 10B), whereby the site marker 80 is compressed into apredetermined size and shape so as to be readily positionable within thedeployment device. In fact, site marker 80 may be positioned in thedeployment device prior to shipping deployment device. Once site marker80 exits the deployment device into the biopsy site, site marker 80 isreleased from its compressed first pre-deployment configuration andautomatically expands into a second post-deployment configuration (shownin FIG. 10A), whereby at least a portion of the body portion 82 of thesite marker 80 expands at least as much as the outside diameter of thedeployment device to form a close cage that holds permanent marker 88such that site marker 80 cannot migrate back into the deployment device.

In another embodiment, as shown in FIG. 10C, an outside surface 87 ofbody portion 82 is provided with one or more barbs 89 disposed thereon.The barbs 89 assist in adhering site marker 80 to internal walls of thebiopsy cavity. Barbs 89 are configured so as to extend at apredetermined angle relative to outside surface 87. In one specificembodiment, barbs 89 are configured to extend perpendicular to outsidesurface 87. In another embodiment, barbs 89 are positioned at differentangles relative to one another, including opposing one another.

In another embodiment, as shown in FIGS. 10D and 10E, body portion 82′of site marker 80′ is manually expanded from a first pre-deploymentconfiguration (FIG. 10D) into a second post-deployment configuration(FIG. 10E). In this embodiment, site marker 80′ is provided with athread 81 or deployment line (e.g., thread, filament, wire) that isattached to the forward end 84′ of body portion 82′. Thread 81 is heldby a tie-wrap style clinch via the deployment device. Once the sitemarker 80′ is deployed, the tie-wrap pulls on thread 81 which pops openbody portion 82′ to the second post-deployment device to a predeterminedmaximum size. Upon reaching the predetermined maximum size, thedeployment device severs thread 81, releasing site marker 80′ into thebiopsy site.

Another embodiment of a site marker 90 is shown in FIGS. 11A and 11B.Site marker 90 is formed as a solid beam defined by relatively planartop and bottom surfaces 92 and 93. When site marker 90 is subjected to apredetermined ultrasound frequency, it resonates, thereby making itvisible under various modalities.

In an alternative embodiment, as shown in FIG. 11B, site marker 90′ mayfurther include a flange 96 attached to an end portion 98 the sitemarker 90 to assist with deployment and/or positioning site marker 90′within the biopsy site.

In one embodiment, site marker 90, 90′ and flange 96 is constructed fromtitanium or other 7uitable material. In another embodiment, site marker90, 90′ is constructed from a solid piece of material such that it hasno sealed chambers or regions that contain gas or air.

In yet another site marker design, the site marker contains a pluralityof solid glass beads that are fused together similar to the sinteredsite marker 24 described above in connection with FIGS. 2A and 2B. Inone embodiment, the glass material has a specific acoustic impedanceratio in the range of 8.2-9.4. The glass balls are fused together suchthat there are no sealed chambers or regions that contain air or gas.

FIG. 12A-12C depict a site marker 100 that is constructed of a foam-likematerial. The foam-like material may be a carbon filled polymer or aglass filled polymer so as to be visible under multiple modalities. Inaddition, the foam-like material may contain therapeutic materials todeliver medication to the biopsy site. One exemplary material forconstruction of site marker 100 is a thrombin filled polymer. Thefoam-like material acts as a matrix for tissue ingrowth.

Site marker 100 expands from a first pre-deployment configuration (shownin FIG. 12B) to a second post-deployment configuration (shown in FIG.12C). In the first pre-deployment configuration, site marker issubstantially compressed in either length or width or both so as to bereceivable within a suitable deployment device. The site marker mayremain in the pre-deployment device for an extended period of time, suchthat it may be desirable to pre-load a deployment device with one ormore of the site markers in the first pre-deployment configuration.

In one embodiment, the material may from which site marker 100 isconstructed is a shape memory material that will spring into the secondpost deployment configuration upon release from a deployment device intoa biopsy cavity. In accordance with this embodiment, the site marker isdesigned to have a predetermined shape and then compressed into thefirst pre-deployment configuration. The site marker is then retained inthe first pre-deployment configuration and may be loaded into adeployment device. It should be noted that the site marker may be storedin the deployment device in the first pre-deployment configuration foran extended period of time.

Once released from the deployment device and into the biopsy cavity, thesite marker automatically springs into the second post-deploymentconfiguration having a predetermined size and shape such that the sitemarker is easily visible under various imaging modalities.

In another embodiment, site marker 100 is constructed of a temperaturedependent material. In accordance with this embodiment, the site markerdoes not expand from the first pre-deployment configuration into thesecond post-deployment configuration until heat is applied to the sitemarker 100. Deploying the site marker 100 into a biopsy cavity providesa sufficient level of heat generated from the body to enable site marker100 to automatically expand into the second post-deploymentconfiguration after deployment.

In another embodiment, shown in FIGS. 13A-13B, a site marker 102 havinga marker head 104 and one or more appendages 106 attached thereto isdisclosed. In this embodiment, the marker head 104 may be a permanentmarker such that it will not become absorbed by the body afterdeployment. Alternatively, however, it is understood that marker head104 may be a bioabsorbable marker that is absorbed by the body by apredetermined time.

In one embodiment, the appendages 106 attached to the marker head 104are semi-rigid and constructed of a heat activated material that causesthe appendages 106 to curl outwardly once received in the body (See FIG.13B). These appendages 106 serve to contact the walls of a biopsy cavityto prevent the marker 102 from migrating outside of the biopsy cavity.

Alternatively, the appendages 106 may be constructed of a memory-shapematerial whereby the appendages 106 are preformed with curled, outwardlyextending ends 108. The appendages 106 are then compressed into apre-deployment configuration, such as that shown in FIG. 13A to enablethe marker 102 to be received within and deployed from a suitabledeployment device. Once the marker 102 is deployed, the appendages 106resume its preformed configuration which enables the appendages 106 toengage the walls of a biopsy cavity to prevent the marker 102 frommigrating.

In another embodiment, as shown in FIG. 13C, appendages 106 may includeone or more barbs 110 that extend outwardly from appendages 106. Barbs110 may be angled relative to appendages 106 and may be arranged on bothtop and bottom surfaces of appendages 106. While FIG. 13C illustratesbarbs 110 being angled in a first direction on a top surface ofappendages 106 and a second direction on a bottom surface of appendages106, it is understood that barbs 110 be oriented on each surface ofappendages 106 in multiple directions. Barbs 110 serve to aid inattaching marker 102 to the walls of a biopsy cavity.

FIGS. 13D and 13E are still a further embodiment of a site marker 112.In this embodiment, site marker 112 includes two marker heads 114 thatare joined together by one or more appendages 116. The appendages 116may include barbs (not shown) and may deform after deployment to a bowedconfiguration (FIG. 13E) to engage the biopsy cavity and preventmigration.

In another embodiment of the present invention, shown in FIGS. 14A-14C,an expandable site marker 120 is disclosed. Site marker 120 is generallyhollow, defining a passageway therethrough and is constructed of astent-like, woven mesh material that acts as a matrix for tissueingrowth. The site marker 120 expands from a first pre-deploymentconfiguration (shown in FIG. 14B) to a second, larger post-deploymentconfiguration (shown in FIG. 14C). In the first pre-deploymentconfiguration, site marker is substantially compressed in either lengthor width or both so as to be receivable within a suitable deploymentdevice. The site marker 120 may remain in the pre-deployment device foran extended period of time, such that it may be desirable to pre-load adeployment device with one or more of the site markers 120 in the firstpre-deployment configuration.

In one embodiment, the material may from which site marker 120 isconstructed is a shape memory material that will spring into the secondpost deployment configuration upon release from a deployment device intoa biopsy cavity. In accordance with this embodiment, the site marker 120is designed to have a predetermined shape and then compressed into thefirst pre-deployment configuration. The site marker 120 is then retainedin the first pre-deployment configuration and may be loaded into adeployment device. It should be noted that the site marker 120 may bestored in the deployment device in the first pre-deploymentconfiguration for an extended period of time.

Once released from the deployment device and into the biopsy cavity, thesite marker 120 automatically springs into the second post-deploymentconfiguration having a predetermined size and shape such that the sitemarker 120 is easily visible under various imaging modalities.

In another embodiment, site marker 120 is constructed of a temperaturedependent material. In accordance with this embodiment, the site marker120 does not expand from the first pre-deployment configuration into thesecond post-deployment configuration until heat is applied to the sitemarker 120. However, deploying the site marker 120 into a biopsy cavityprovides a sufficient level of heat generated from the body to enablesite marker 120 to automatically expand into the second post-deploymentconfiguration after deployment.

Yet another embodiment of a site marker 122, is shown in FIG. 15A. Whensite marker 122 is in a deployed configuration, as shown in FIG. 15A, ithas a tetrahedron shell defined by external spines or ribs 124 that arepre-biased so as to form the tetrahedron shape. The spines 124 areconnected together by a woven web material that permits tissue ingrowthto create the tetrahedron shell In one embodiment, tetrahedron shell isbioabsorbable such that after a predetermined time, the shell iscompletely absorbed by the body.

Contained within the tetrahedron shell is a marker 126 that is visibleunder one or more modalities. By having the marker 126 contained withinthe shell, the marker 126 is prevented from migrating. Indeed, themarker 126 may only move within the shell. In one embodiment, marker 126is a permanent marker that will not become absorbed by the body.Alternatively, marker 126 may be a non-permanent marker that remainswithin the body for a predetermined length of time.

In an alternative embodiment, site marker 122′ may be formed to have adouble tetrahedron shell as shown in FIG. 15B. The double tetrahedronsite marker 122′ design is similar to the single tetrahedron site marker122 in that it also is defined by external spines 124′ that arepre-biased into the deployed configuration, as shown in FIG. 15B.

Both site marker 122 and 122′ may be compressed into a firstpre-deployment configuration, such as that shown in FIG. 15C. In thisconfiguration, site markers 122 and 122′ are substantially compressed ineither length or width or both so as to be receivable within a suitabledeployment device. The site markers 122 and 122′ may remain in thepre-deployment device for an extended period of time, such that it maybe desirable to pre-load a deployment device with one or more of thesite markers 122 or 122′ in the first pre-deployment configuration.

Once deployed by a suitable deployment device or released from thefirst, pre-deployed configuration, the pre-biased spines 124, 124′ ofsite markers 122 and 122′ automatically return to site markers 122 and122′ to the deployed configurations shown in FIGS. 15A and 15B.

Yet another embodiment of a site marker 128 is shown in FIG. 15D. Inthis embodiment, a tube 130 that is formed of a mesh-like material isprovided. Internal spines 132, including base spines 133, are positionedwithin tube 130 that are pre-biased to form a tetrahedron shell withintube 130 when in a deployed configuration. A marker 134 is positionedwithin the tetrahedron shell such that the marker is prevented fromundesirable migration within the biopsy cavity.

In yet another alternative embodiment, base spines 133 are eliminatedsuch that the remaining spines 132 within tube 130 are biased to formcapped ends when the site marker 128 is in a deployed configuration.

To deploy the embodiments described in connection with FIG. 15D, thesite marker 128 must be compressed into suitable size and shape toenable it to be received, stored and translated within a deploymentdevice. Once the site marker 128 is deployed from the device, thepre-biased internal spines 132 and 133, will automatically return thesite marker 128 into the deployed configuration.

FIG. 16A illustrates a partial cross sectional view of anotherembodiment of a site marker 200 that is similar to the embodiment shownin FIG. 10E. Site marker 200 includes a body portion 202, which is shownin a post-deployment configuration. In this embodiment, site marker 200is provided with a thread 203 or deployment line (e.g., thread,filament, wire) that is attached to and extends between a forward end204 and a rearward end 206 of body portion 202. Body portion 202 of sitemarker 200 is manually expanded from a first pre-deploymentconfiguration (i.e., FIG. 10D) into the second post-deploymentconfiguration by thread 203 or deployment line. More specifically,thread 203 is pre-biased to spring forward and rearward ends 204, 206away from on another. A permanent marker 208 is positioned within bodyportion 202 and need not be attached to body portion 202 in any way.Instead, marker 208 may float freely within body portion 202.

In yet another embodiment of a site marker 210, as shown in FIG. 16B, abody portion 212 has at least one marker 214 that is held in place bydeployment line 216. Marker 214, which may be a permanent marker thatdoes not break down and become absorbed by the body for a predeterminedtime period, includes a through hole 218. Accordingly, deployment line216 is received in through hole 218 such that marker 214 may selectivelyslide along deployment line 216. While marker 214 is shown as having adonut shape, it is understood that any body with a through hole able toaccommodate the deployment line 216 such as, but not limited to, a ring,helical shape or tube that is able to slide along deployment line 216without departing from the invention. In one embodiment, afterinstallation in a biopsy cavity, over a predetermined time period suchas three weeks to six months, body portion 212 is absorbed by the body,such that only marker 214 remains within the body at the biopsy cavity,and is visible under one or more modalities.

As mentioned above, marker 214 may be a permanent marker that is notabsorbed by the body. Alternatively, marker 214 may be a semi-permanentmarker that absorbs slower than body portion 212. Because the movementof marker 214 is restricted by deployment line 216 prior to absorptionthereof by the body, marker 214 is restricted from migrating from withinthe biopsy cavity. Indeed, movement of marker 214 is limited along thedeployment line 216. This insures that marker 214 remains within thebiopsy cavity to permit follow-up imaging of the biopsy site.

In yet another alternative embodiment, a site marker 220, as shown inFIG. 16C, includes a body portion 222 and at least one marker element224. Similar to the embodiment depicted in FIG. 16B, marker element 224includes a through hole 226 that receives a deployment line 225. In theembodiment shown, marker element 224 has an elongated profile, similarto a tube. However, it is understood that other shapes of marker 224 maybe utilized. Marker element 224 may be at least partially retained by afilament 228, where filament 228 is bonded to an end of body portion222. In one embodiment, filament 228 forms a loop around a portion ofmarker element 224, to hold marker 224 in position within body portion222 in addition to deployment line 225.

After installation in a biopsy cavity, over a predetermined time periodsuch as three weeks to six months, body portion 222 is absorbed by thebody, such that only marker 224 remains within the body at the biopsycavity. Because marker 224 is restricted along deployment line 225, andis further constrained by filament 228, marker 224 is restricted frommigrating from within the biopsy cavity. Indeed, movement of marker 224is limited along the deployment line 225 and is further constrained byfilament 228. This insures that marker 224 remains within the biopsycavity to permit follow-up imaging of the biopsy site.

Yet another embodiment of a site marker 230 is shown in FIG. 16D. Sitemarker 230 includes a body portion 232 and at least one marker element234. In this embodiment, marker element 234 is restrained only byfilament 236. Once site marker 230 exits a deployment device into thebiopsy site, site marker 230 is released from a pre-biased andcompressed first pre-deployment configuration and automatically expandsinto a second post-deployment configuration (shown in FIG. 16D). Becausemarker 234 is restricted by filament 236, marker 234 is restricted frommigrating from within the biopsy cavity. Indeed, movement of marker 234is limited along filament 236. This insures that marker 234 remainswithin the biopsy cavity to permit follow-up imaging of the biopsy site.

In yet another embodiment of a site marker 240, as shown in FIG. 16E,includes a body portion 242 that has a hollow deployment line 244.Deployment line 244, which is shown in cross sectional view, is designedso as to be able to accommodate at least one marker 246. Marker 246 isconstructed such that it has a smaller outside periphery than the innercircumference of hollow deployment line 244. Marker 246 is able toselectively slide inside of hollow deployment line 244. Because themovement of marker 246 is restricted by hollow deployment line 244 priorto absorption thereof by the body, marker 246 is restricted frommigrating from within the biopsy cavity. Indeed, movement of marker 246is limited along hollow deployment line 244. This insures that marker246 remains within the biopsy cavity to permit follow-up imaging of thebiopsy site.

While the present invention has been particularly shown and describedwith reference to the foregoing preferred embodiments, it should beunderstood by those skilled in the art that various alternatives to theembodiments of the invention described herein may be employed inpracticing the invention without departing from the spirit and scope ofthe invention as defined in the following claims. It is intended thatthe following claims define the scope of the invention embodimentswithin the scope of these claims and their equivalents be coveredthereby. This description of the invention should be understood toinclude all novel and non-obvious combinations of elements describedherein, and claims may be presented in this or a later application toany novel and non-obvious combination of these elements. The foregoingembodiment is illustrative, and no single feature or element isessential to all possible combinations that may be claimed in this or alater application.

What is claimed is:
 1. A site marker, comprising: a generally hollowbody portion that defines a cavity therein; a filament secured to an endof said body portion; and at least one marker element wherein saidfilament is secured to said marker element; thereby limiting migrationof said marker element.
 2. The site marker of claim 1, wherein saidfilament is formed into a loop that is received within a through holeformed through said marker element.
 3. The site marker of claim 1,wherein said filament has a predetermined length such that said markerelement is retained closer to one end of said body portion.
 4. The sitemarker of claim 1, wherein said hollow body portion is constructed of abioabsorbable material.
 5. The site marker of claim 4, wherein saidbioabsorbable material is one of polyglycolic acid, polylactic acid,hydrogel, and collagen-based material.
 6. The site marker of claim 4,wherein said body portion is absorbed by a mammalian body after apredetermined time period.
 7. The site marker of claim 4, wherein saidmarker element is permanent such that said marker element is notbioabsorbable.
 8. The site marker of claim 7, wherein said markerelement is visible under multiple imaging modalities.